Megalourethra is a rare congenital anomaly characterized by dilatation of the penile urethra which causes functional obstruction of the lower urinary system. We present a case of congenital megalourethra diagnosed prenatally. Transabdominal sonography revealed a male fetus with bilateral hydroureter, hydronephrosis, dilated bladder and normal amniotic fluid. The fetal penis was enlarged and the penile urethra was dilated with ballooning at the distal end. The urethral meatus was identified. The fetus was delivered at term with a favorable outcome.